1. Field of the invention
This invention relates to an interface circuit of quick response type used in a Central Office Terminal (referred to hereinafter as COT) connected with a switching station.
2. Description of the Related Arts
In an interface circuit provided in a COT connected with a switching station SW, when a subscriber picks up the receiver of his telephone set TEL in response to the ring, a loop circuit, i.e., a speech path, has to be quickly established with the switching station.
However, if the COT is distantly located from the switching station the resistance of the telephone line L becomes so large as to cause a delay of a ring-trip operation in establishing the speech path, due to an increase of time constant of the interface circuit.